Many advocates of weight loss diets make blanket statements about the dangers of carbohydrates when it comes to losing weight. That is so wrong. Although there are some carbohydrates that are bad for a diet in general, many carbs are good and in fact are essential for our survival. The aim of this article is to help you understand what are carbohydrates and help you make right carbohydrate choices for your healthy diet.
What Are Carbohydrates – Simplified
Carbohydrates are essential macronutrients to sustain human life. The other macronutrients are proteins and fats. Roughly half of our energy to function comes from glucose and its storage form glycogen. In order for our bodies to produce glucose and glycogen, we need to consume carbohydrate rich foods.
We convert part of carbohydrates we eat to glucose for immediate energy and the rest is stored as glycogen and fat for future energy requirement.
The dietary carbohydrates come in two forms: simple carbohydrates (for example sugar) and complex carbohydrates (starches and fiber).
What Are Simple Carbohydrates
Simple carbohydrates are small molecules that consist of
- a single sugar molecule (monosaccharides) such as glucose, fructose and galactose. Fructose, for example is found in fruits.
- a double sugar molecules (disaccharides) which consist of pairs of the monosaccharides. The disaccharides are maltose (glucose + glucose), sucrose (glucose + fructose) and lactose (glucose + galactose). For example, the white sugar we normally eat is a sucrose and lactose is found in milk.
Simple carbohydrates are found naturally in fruits and dairy. They are also found in processed and refined foods. Of these the most common ones are table sugar (white sugar), milk and dairy products, white bread, pastas, white rice, jams, salad dressings, pastries. The list is endless, all you need to do is check the nutrient label of any processed food.
What Are Complex Carbohydrates
Complex carbohydrates are called polysaccharides. They are large molecules mostly made up of chains and links of glucose molecules.
Starch is the energy storage form in the plants. It is composed of a multitude of glucose molecules. Both, starch and fiber are found in grains, potatoes, legumes and brown rice, among others. In the body the starch is metabolized into glucose and in turn to energy.
Glycogen is the storage form of energy in animals including humans. Glycogen is not a significant food source of carbohydrates.
Fiber is a nonstarch polysaccharide and it provides structure to the various parts of plants. It’s chemistry is such that it cannot be broken down by our digestive enzymes. Fiber plays a significant role in our gastro-intestinal tract function and nutrient absorption and contributes greatly to our health. Learn more about fiber and dietary fiber requirements in the post dietary fiber article.
Of the three types of complex carbohydrates, from a dietary point of view, only starch and fiber are of essence.
What Do Carbohydrates Do For The Body
Carbohydrates must be digested and absorbed in order to transform into the energy for immediate or future use by our bodies. During the process the carbohydrates (not fiber) are converted to glucose, glycogen or fat. Glucose is then forwarded to the organs or tissues that require energy.
As glucose is an essential fuel for the body and the brain, it is constantly present in the blood stream at a certain level. This level is called the glycemia level. In a healthy body our pancreas and its hormone insulin work in concert to insure that the glycemia level remain normal at all times.
During the breakdown of carbohydrates to glucose, complex carbohydrates facilitate a slow release of glucose into the blood stream, where as simple carbohydrates cause a rapid and a significant rise in glucose in the blood. In response, pancreas secrets insulin into the blood stream, which lowers the glucose.
Insulin, is an important hormone that is central to regulating carbohydrate and fat metabolism in the body. It also facilitates the storage of excess carbohydrate calories as fat.
Too many simple carbohydrates in the diet promote weight gain because of too much of glucose and hence insulin in the blood stream. High insulin levels suppress two important hormones: glucagon and human growth hormone, which regulate the burning of fat and promote muscle development, respectively. In other words, insulin from excess carbohydrates promotes fat, then inhibits the body’s ability to lose that fat.
Dividing carbohydrates into simple and complex makes sense on a chemical level. But it doesn’t do much to explain what happens to different kinds of carbohydrates inside the body. For example, the starch in white bread and French-fried potatoes clearly qualifies as a complex carbohydrate. Yet the body converts this starch to blood sugar nearly as fast as it processes pure glucose. Fructose (fruit sugar) is a simple carbohydrate, but it has a minimal effect on blood sugar.
A new system, called the glycemic index, aims to classify carbohydrates based on how quickly and how high they boost blood sugar compared to pure glucose…(Source)
Glycemic Index Of Carbohydrates
Because the body converts different types of carbohydrates into sugar at different rates, the glycemic index (GI) was established to indicate how quickly a food affects blood sugar level. Foods that have a low GI cause a slow increase of glucose in bloodstream and a slow and controlled insulin release. On the other hand, foods that have a high GI cause a rapid increase in glucose levels thus rapid increase in insulin, which is not what you want when trying to lose weight and maintain good health.
Foods with a score of 70 or higher are defined as having a high glycemic index (bad carbohydrates); those with a score of 55 or below have a low glycemic index (good carbohydrates). Find out more about glycemic index and the bad and good carbohydrates here…
As I mentioned already the primary role of carbohydrates is to produce energy. Any excess will be processed and turned into glycogen or fat.
Glycogen is a large structure and it is made up of many units of glucose. When a body is in need of energy and there is a lack of glucose in the blood stream it will turn to glycogen stores for energy. Glycogen is stored in the liver and muscles. Unfortunately, our ability to make glycogen is finite. In other words the amount of glycogen our bodies can make is limited. Once the body reaches its glycogen limit the excess glucose will be turned into fat. One can increase the glycogen storing capabilities by exercising and building muscles which will accommodate more glycogen.
Fats are made when there more glucose remains in the blood stream after the energy requirements are met and the glycogen limits are reached. The liver breaks down excess glucose into smaller units and links them back together into different structures, called fatty acids. These are released into the bloodstream and eventually will find their way into adipose tissue or the fat tissue stores. There they form larger molecules called triglycerides and are stored as fats. They are released when energy is needed.
Daily Requirement Of Carbohydrates
Although recommendation vary, the general belief is that 55-60% of our daily calorie intake should come from carbohydrates. They are the most accessible source of energy. 1 gram of carbohydrates equals 4 calories of energy. It is recommended that most of this energy comes from complex carbohydrates such as fruits, vegetables and grains rather than sugary and refined foods.
In conclusion, carbohydrates are the mainstay of life. Over the years carbohydrates got a bad rap and many people shun carbohydrates all together. However, as you can see not all carbohydrates are equal. You still can eat carbohydrates, even when you are trying to lose weight. The goal to a successful weight loss is to find and consume the right quantity and quality of carbohydrates that provide fuel and energy for the day and make one feel good and satiated after the meal. Now that you know what are carbohydrates and how important are they for our diets, nothing stops you to enjoy them and still lose weight.
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